EMAs comprise systems capable of moving a moveable member, such as ram or “puck,” A ram may be positioned to forcefully engage one or more components of a brake disk stack, for example, generating braking force. Thus, EMAs may be found in various braking systems, including for example brakes used with aircraft wheels.
An EMA may comprise an actuator drive unit (“ADU”). The ADU may itself comprise a motor and a motor housing (also referred to as an ADU housing). The motor may cause a ball screw to rotate about the ADU housing.
A separate support structure may support rotation of the ball screw about the ADU housing. A plurality of ball bearings may circulate within the support structure to facilitate rotation of the ball screw about the ADU housing. Thus, a ball screw may be referred to as a “rotating race,” while an ADU housing may be referred to as a “static race.”
As the ball screw rotates on the support structure over the ADU housing, a cylindrical ball nut situated over an outer surface of the ball screw may translate in an axial direction over a separate plurality of balls circulating within a raceway or channel formed between the ball screw and the ball nut. Thus, the ball nut may translate axially over the ball screw, as the ball screw rotates. As the ball nut advances, the ram or puck, which may be coupled to the ball nut, may apply a braking force.